Various sporting rifles or pistols are known in the state of the art that adapt to various output powers depending on the country. For this, they employ springs in the sporting rifle or pistol chamber.
The applicant company of Spanish Utility Model No 0210145 “PNEUMATIC RIFLE WITHOUT RECOIL EFFECT”, of 1975, currently in the public domain, which refers to a pneumatic rifle without recoil effect, essentially characterised in that the assembly comprising the pneumatic chamber, barrel, air compressor piston and drive spring, together with the associated housing and securing components form a mobile group that is forward when the rifle is loaded by breaking the barrel, remain retained during the time in which the rifle is loaded and which is released, permitting its movement, after the same is fired, compensating said recoil movement that of the conventional rifle recoil, due to the reaction produced by the shock of the piston against the front part of the chamber. FIGS. 1 and 2 of reference 17 show the output power regulator spring or drive spring.